Question

state Snell's. law of refraction

Answer 1

According to Snell's law of refraction, the ratio of sine of angle of incidence and sine of angle of refraction is always constant for a given pair of medium.
Hope it helps

Answer 2

it states that, "ratio of the sines of the angles of incidence and refraction of a wave are constant when it passes between two given media"
$n = \frac{ \sin(i) }{ \sin(r) }$